Multilayered prosthesis material and a method of producing same

Abstract

A method producing a multilayered prosthesis material for use with a living body, said material showing mechanical compliance vis-a-vis soft body tissue and possessing biocompatibility. The method comprising the steps: (a) preparing a copolymer solution using a solvent; (b) coating a substrate with a uniform thickness of said solution; (c) precipitating the initial coating resulting from step (b) to form a physically stable structure having pores substantially uniformly distributed therein by treating the coating with a precipitating solution which is miscible in said solvent but functioning as a precipitating non-solvent with respect to the copolymer; and (d) repeating steps (a)-(c), as required to form the multilayered material, characterized by preparing in step (a) a solution containing less than 5% by weight of polymer. Also disclosed is a multilayered prosthesis material possessing biocompatibility and showing mechanical compliance vis-a-vis soft body tissue, comprising several porous layers of block copolyurethane interconnected by linking fibers integral with the respective adjacent layers.

What is claimed is: 
     
       1. A method of producing a multilayered prosthesis material for use with a living body, said material showing mechanical compliance vis-a-vis soft body tissue and possessing biocompatibility, said method comprising the steps: (a) preparing a polymer solution using a solvent wherein said polymer solution contains less than 5% by weight of polymer;   (b) coating a substrate with a uniform thickness of said solution;   (c) precipitating the intial coating resulting from step (b) to form a physically stable structure having pores substantially uniformly distributed therein by treating the coating with a precipitating solution which is miscible in said solvent but functioning as a precipitating non-solvent with respect to the polymer; and   (d) repeating steps (a)-(c), as required , to form a multilayered material.   
     
     
       2. The method of claim 1, wherein the solution prepared in step (a) contains less than about 3% by weight of polymer. 
     
     
       3. The method of claim 1, wherein at least a portion of the solvent is left in each preceding layer when the subsequent layer is applied. 
     
     
       4. The method of claim 3, wherein the precipitating solution comprises as a major constituent, a fluid which is miscible in said solvent but functions as a precipitating non-solvent with respect to the polymer, and further comprises as a minor constituent, a solvent for the polymer, whereby when repeating steps (a)-(c), due to the presence in the precipitating solution of solvent, mechanical binding will be obtained between said initial coating and the subsequent one. 
     
     
       5. The method of claim 3, wherein the treatment of the coating with the precipitating solution is interrupted so that a portion of the solvent is left in the coating when the subsequent layer is applied. 
     
     
       6. A method according to claim 1, wherein said polymer solution contains a copolyurethane. 
     
     
       7. A method according to claim 6, wherein the polymer is a segmented copolyurethane. 
     
     
       8. A method according to claim 1, wherein the solvent is selected from the group consisting of tetrahydrofurane, amide solvents and sulfoxide solvents. 
     
     
       9. A method according to claim 1, wherein the non-solvent is selected from water and lower alkanols. 
     
     
       10. The method of claim 1, wherein by varying the concentration of polymer in the solution of step (a) a multilayered material is produced wherein the different layers have different average pore sizes. 
     
     
       11. The method of claim 2, wherein the solution prepared in step (a) contains less than about 2% by weight of polymer.